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([2600:1010:b067:e6ce:10dd:e058:94b7:feca]) by smtp.gmail.com with ESMTPSA id e17sm9438491pgg.5.2019.11.02.15.30.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 02 Nov 2019 15:30:50 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Andy Lutomirski Mime-Version: 1.0 (1.0) Subject: Re: [RFC PATCH 11/10] pipe: Add fsync() support [ver #2] Date: Sat, 2 Nov 2019 15:30:49 -0700 Message-Id: References: Cc: David Howells , Konstantin Khlebnikov , Rasmus Villemoes , Greg Kroah-Hartman , Peter Zijlstra , Nicolas Dichtel , raven@themaw.net, Christian Brauner , keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-block , LSM List , linux-fsdevel , Linux API , Linux Kernel Mailing List In-Reply-To: To: Linus Torvalds X-Mailer: iPhone Mail (17A878) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Nov 2, 2019, at 3:04 PM, Linus Torvalds = wrote: >=20 > =EF=BB=BFOn Sat, Nov 2, 2019 at 1:31 PM Andy Lutomirski wrote: >>=20 >> Add in the fact that it=E2=80=99s not obvious that vmsplice *can* be used= correctly, and I=E2=80=99m wondering if we should just remove it or make it= just do write() under the hood. >=20 > Sure it can. Just don't modify the data you vmsplice. It's really that sim= ple. So you allocate memory, vmsplice, and munmap() without reusing it? Just pla= in free() won=E2=80=99t be good enough. I suspect the TLB overhead will make= this a loss in most workloads? Or maybe you vmsplice from a read-only mapping of a file that you know no on= e modifies? This could be useful, but you can just splice() from the file d= irectly.=